1. Field of the Disclosure
The present disclosure relates to a molded case circuit breaker, and particularly, to a molded case circuit breaker in which by improving a structure of a dial included in the molded case circuit, a rated current is adjusted without an error, a whole structure is simplified, the manufacturing cost is reduced, and the dial fixed to the molded case circuit breaker is prevented from easily deviating from the molded case circuit.
2. Background of the Disclosure
Generally, a molded case circuit breaker (MCCB) is installed on a switchboard among power distribution equipment provided in factories, buildings, and/or the like. In a non-load state, the molded case circuit breaker acts as a switching device that supplies or cuts off power to a load. While a load is being used, when a high current higher than a load current flows due to an abnormal condition that occurs in a load electric circuit, the molded case circuit breaker acts as a circuit breaker that supplies or cuts off power supplied from a power source to a load, for protecting a wire of an electric circuit and elements of the load.
As described above, when an error occurs in a circuit, the molded case circuit breaker quickly breaks an electric circuit, thereby preventing a wiring and a connection device from being damaged or preventing fire.
FIG. 1 illustrates a schematic configuration of a related art molded case circuit breaker.
As illustrated in FIG. 1, the related art molded case circuit breaker includes: a fixed contact 1 that is supplied with power through a general cable and transfers the power to a load; a movable contact 2 that is brought in contact with or separated from the fixed contact 1 and applies the power to the fixed contact 1; an extinguishing apparatus 3 that extinguishes an arc when cutting off a fault current; an opening/closing mechanism 4 that opens or closes an electric line; a detection mechanism 5 that detects an abnormal current; and a case 6 that includes a plurality of elements disposed therein.
FIG. 2 is a schematic perspective view illustrating the detection mechanism 5 included in the related art molded case circuit breaker. FIG. 3 is an exploded perspective view illustrating a detection mechanism cover included in the detection mechanism 5. FIG. 4 illustrates a dial for adjusting a rated current of the related art. FIG. 5 illustrates a schematic plan view of a dial mount. FIG. 6 illustrates a schematic perspective view of a trip mechanism and a detection unit.
As illustrated in FIGS. 2 to 6, the detection mechanism 5 may include a detection mechanism cover 5a, a detection mechanism case 5b where a plurality of elements are disposed, a trip mechanism 5c that is tripped when a fault current is applied to the molded case circuit breaker, and a detection unit 5d that detects the fault current. A dial 5e, which displays and adjusts a rated current, and a dial mount 5f that fixes the dial 5e are disposed in the detection mechanism cover 5a. 
In this case, the dial 5e includes a maximum stopper 5e-1 and a minimum stopper 5e-2, which limit a rotation of the dial 5e, and a moving bar 5e-3 that moves a crossbar 12 to adjust the trip mechanism 5c. 
Moreover, the dial mount 5f includes a dial coupling hole 5f-1 and a fixing stopper 5f-2. The maximum stopper 5e-1 and the minimum stopper 5e-2 are brought in contact with the fixing stopper 5f-2 according to the dial 5e being rotated with the dial 5e being fitted into the dial coupling hole 5f-1, and thus, the rated current of the molded case circuit breaker is adjusted.
Therefore, when a fault current equal to or higher than the rated current which has been adjusted through the dial 5e flows into the molded case circuit breaker, a bimetal 11 is bent toward the crossbar 12 due to heat generated by a heater 10 and rotates the crossbar 12 by pushing an inclined surface of the crossbar 12 to release a restraint of a shooter 13, thereby enabling the opening/closing mechanism 4.
In the molded case circuit breaker that is configured and operates as described above, the dial 5e is rotated by adjusting the rated current. When the dial 5e is counterclockwise rotated in a state where the rated current is set by 100%, the crossbar 12 is moved to the left (a direction toward the bimetal 11) through the moving bar 5e-3 included in the dial 5e, and thus, the inclined surface of the crossbar 12 is moved to the left (the direction toward the bimetal 11), whereby a size of a gap between the crossbar 12 and the bimetal 11 is adjusted and thus a value of the rated current is variously set.
However, as described above, in the dial 5e of the related art for adjusting the rated current of the molded case circuit breaker, it is difficult to accurately match the dial 5e with a desired value of the rated current when rotating the dial 5e. 
Moreover, there is no separate element for fixing the dial 5e to an adjusted position, and thus, when an impact is applied from the outside to the molded case circuit breaker, the dial 5e is rotated to a certain degree, whereby a rated current value of the molded case circuit breaker is changed. For this reason, despite a fault current being applied to the molded case circuit breaker, a trip operation cannot be performed.